Phase II Environment and Geotechnical Ground Investigation

Phase II Environment and Geotechnical Ground Investigation

A Cost Effective Targeted Remediation Strategy

A Phase II environmental ground investigation gets its name from the protocols determined by the planning process and is undertaken following a (Preliminary) Conceptual Site Model (CSM) as assessed by a Phase I report.  For more information on Phase I reports please see our page on the subject here.

A Phase II should be undertaken when a Phase I report has determined that at least one Pollutant Linkage exists and possesses a risk rating sufficiently high enough that further investigation is needed to find out more about that pollutant linkage.

Every pollutant linkage is associate to what is known as a Contaminant of Concern (CoC), be it a metal such as Lead, old fuel such as heating oil, sprays and aerosols or hazardous ground gases.  Every CoC can have more than one pollutant linkage, they all need investigating.

In a Phase II ground investigation, we are looking at three types of pollutant linkage:

• The potential contaminants on site acting on receptors on site,
• The potential contaminants on site acting on receptors adjacent to the site,
• The potential contaminants adjacent to the site acting on receptors on site.

This requires the site investigation specialist to obtain samples of soil and, if present, groundwater, local surface water (if neighbouring the site), even hazardous ground gases (Methane, Carbon Dioxide, Carbon Monoxide, Hydrogen Sulphide and even, if appropriate, Radon) in order to positively identify, or just as importantly, to discount the contaminant is impacting any of the potential receptors identified above.

The aim of the Phase II ground investigation is to take the preliminary CSM as defined by the Phase I report and investigate the pollutant linkages in order to refine the CSM into what is commonly known as an updated CSM, this time based on actual site conditions.  The updated CSM can either close off a pollutant linkage – i.e., proving that although there was a theoretical risk form a pollutant linkage, none actually exists or confirm that the pollutant linkage exists.

If a pollutant linkage exists, depending on what is going to be built on the site under consideration, it could be that the presence of that particular CoC isn’t an issue for the site (e.g., building a factory) or that something needs doing to rectify the situation and remove that pollutant linkage, a process known as remediation.  For more information on remediation please read our page on the subject.

As explained at the beginning of this page, a PII ground investigation is so-called as part of the planning process.  However, you may want to know all this information for your own purposes, such as buying a site, obtaining funding against the land as an asset, or for a land condition report.  Quite often this type of investigation will still be called a PII, but technically it isn’t.

The other type of ground investigation we carry out at GES is where contamination isn’t an issue, but you may still need to know the geotechnical ground conditions for designing foundations.  A typical example of this would be where a PI report has identified no risks from contamination, but you still need to know what foundations are needed.  This type of investigation is known as a Geotechnical Ground Investigation.

Traditionally, if both were required the two investigations would have been carried out separately, by two different specialists, an environmental one and a geotechnical, one but as both use exactly the same techniques; trial pits, boreholes, etc., it is much more cost effective to combine both investigation and use a specialist such as GES, where we have expertise in both skill sets.

Choosing your site investigation specialist is important as, especially from the contamination perspective, a bad investigator can cause more harm than good!  Here at GES, we have years’ worth of experience to help us provide you with the most appropriate ground investigation, targeted to your needs.